View source for 2iyn

[[Image:2iyn.gif|left|200px]]<br /><applet load="2iyn" size="350" color="white" frame="true" align="right" spinBox="true" 
caption="2iyn, resolution 2.08&Aring;" />
'''THE CO-FACTOR-INDUCED PRE-ACTIVE CONFORMATION IN PHOB'''<br />

==Overview==
PhoB is an Escherichia coli transcription factor from a two-component signal transduction system that is sensitive to limiting environmental phosphate conditions. It consists of an N-terminal receiver domain (RD) and a C-terminal DNA-binding domain. The protein is activated upon phosphorylation at the RD, an event that depends on Mg(2+) binding. The structure of PhoB RD in complex with Mg(2+) is presented, which shows three protomers in the asymmetric unit that interact across two different surfaces. One association is symmetric and has been described as a non-active dimerization contact; the other involves the alpha4-beta5-alpha5 interface and recalls the contact found in activated PhoB. However, here this last interaction is not perfectly symmetric and helix alpha4, which in the activated molecule undergoes a helical shift, becomes strongly destabilized in one of the interacting monomers. All protomers bind the cation in a similar manner but, interestingly, at the prospective binding site for the phosphate moiety the side chains of either Glu88 (in helix alpha4) or Trp54 alternate and interact with active-site atoms. When Glu88 is inside the cavity, helix alpha4 is arranged similarly to the unliganded wild-type structure. However, if Trp54 is present, the helix loses its contacts with the active-site cavity and vanishes. Accordingly, the presence of Trp54 in the active site induces a flexible state in helix alpha4, potentially allowing a helical shift that phosphorylation would eventually stabilize.

==About this Structure==
2IYN is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=MG:'>MG</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Known structural/functional Site: <scene name='pdbsite=AC1:Mg+Binding+Site+For+Chain+C'>AC1</scene>. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2IYN OCA]. 

==Reference==
The cofactor-induced pre-active conformation in PhoB., Sola M, Drew DL, Blanco AG, Gomis-Ruth FX, Coll M, Acta Crystallogr D Biol Crystallogr. 2006 Sep;62(Pt 9):1046-57. Epub 2006, Aug 19. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=16929106 16929106]
[[Category: Escherichia coli]]
[[Category: Single protein]]
[[Category: Blanco, A G.]]
[[Category: Coll, M.]]
[[Category: Drew, D L.]]
[[Category: Gomis-Ruth, F X.]]
[[Category: Sola, M.]]
[[Category: MG]]
[[Category: activation of the pho regulon]]
[[Category: activator]]
[[Category: alpha/beta doubly wound fold]]
[[Category: dna- binding]]
[[Category: dna-binding]]
[[Category: gene regulation]]
[[Category: phosphate regulation]]
[[Category: phosphate transport]]
[[Category: phosphorylation]]
[[Category: sensory transduction]]
[[Category: transcription]]
[[Category: transcription factor]]
[[Category: transcription regulation]]
[[Category: transport]]
[[Category: two-component regulatory system]]

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:57:31 2008''